Radio receiving instrument for systems of broadcast distribution



May 22, 1928.

E. E. CLEMENT RADIO RECEIVING INSTRUMENT FOR SYSTEMS OF BROADCAST DISTRIBUTION 2 Shgeis-Sheet 1 Filed March 13, 1924 Ii a 6. Z

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May 22, 1923'.

E. E. CLEMENT RADIO RECEIVING INSTRUMENT FOR SYSTEMS OF BROADCAST DISTRIBUTION Filed March 15, 1924 2 Sheets-Sheet 2 meter, employing the ener an otherwise be lost in choke coils and the like.

1 Patented may 22, 1928.

i UNITED ST TES v 1, 10,760 f PATENT OFFICE.

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RADIO RECEIVING INSTRUKENT FOR SYSTEMS OF BRGADGAS'I' DISTRIBUTION.

Application fled 13, 18%. Serial Ho. 689,028.-

Myinvention relates to systems of radio broadcast distribution, and has for its object the supply ofcurrent for all p oses to subscribers stations .from a contra station or station's. An ancillary object is to arrange radio telephone subscribers stations so that they may be identified with telephone subscribers lines, supplied with current for all purposes of radio I'QCGIV? 10 ing, 'over said telephone lines and from the standard centralized batteries employed in ,modern telephone exchanges, withoutsubstantially changin any central ofiice circuits or apparatus, an without disturbing the functions of the same as telephone apparatus per se.

I attain my objects in the iollowi ner: .1 provides. receiving set, whic have the usual or any suitable form of aintenna or wave collector, with an input circuit coupled to the wave collector, an output circuit coupled to the wired circuit or telephone line leading to battery terminals; and

I connect the elements of the detector in arallel, in such manner as to differentiate etween incoming battery current and outmangoing modulated current at the substation terminals. In particular, I have'discovered that the filament circuit of a detector tube may be'treated as a parallelbranch of the late circuit for feed purposes, provided diierentiation is made as beiore stated.

In applying this inventionto wired circuits as' such, it'is necessary to provide for' as supervision and maintenance from central, and it is desirable to provide for metering the substation service at the central oflice,

all as set forth in my prior co nding application Serial No. 581,829, ed August 14',

40 1922, patented January 6, 1925, as No.

1,522,357, and' reissued December 15, 1925, as No. 16,231.' The matter of metering is not disclosed herein, and formsno part of the present invention, but it is pointed out that the flow of current for filament supply battery curin the line, being unmodulated rent of perceptible wattage, can conveniently .be used foroperating a central ofiice that would For supervision, the plate circuit of the tube at the substation is included as a part .of the line circuit, and therefore the changes that take place at the subscribers station, which 65' become audibleto him receivingtale;

in the circuit, finding may;

pan'ying drawings, in which amo'n source of current supply.

with choke coils in the bridge, and a bridged receiving telephone, with an audio condenser in the bridge. The choke coils prevent short circuiting of the modulated pulsating cur: rent from the plate through the main bat.- tery, and the condenser keeps ob'ectionable battery current out of the receiving telephone. I use no phone condenser as, such it unnecessary, and it will be understood that in adjusting resistances the apparatus provided is a maximum, to suit the shortest lines, the line resistance as such being disregarded. In commercial practice, instead of using variable resistance, it is obvious that each line, having a known resistance, may be balanced once .for all, by inserting the proper fixed resistance in the filament circuit at the substation. The battery connection I have men'- tioned is one form only. Another standard method of connecting a central battery is between the two halves of a split repeating I practice and in accord. with the arrange: ment .of practically all modern-telephone exchange systems. I

In testing out this circuit, the maximum current flow, using a .UV1'99 tube, was 45 .milliam' res, at maximum efficiency. As

this is ess than the current required forv energization of a standard common battery telep one, it obviously comes well within the limits prescribed by good practice.

My invention is illus'trated'in the accom Fig. 1 is 'ajdlagram showing subscribers radio receiving circuits, connected to-a com- 5 Fig. 2 is a similar'dia n showing re ceiving telephones at the attery end of the su ply "circuit.

diagram of a complete subno "suggest t emselves, butthese two are stand-.

scribers station and line extending to a central oflice equipped with standard jacks, plugs, and cord circuits, and with a common centralized battery adapted to beconnected to subscribers lines through said jacks, plugs and cord circuits.

Fig. 4 is a fragmentary diagram showing a dynamic receiver which may be substituted for the headphone receiver shown in Fig. 3. The parts included within the dotted lines in this figure may be substituted for parts included within the dotted lines in Fig. 3 without other change.

Referring to the drawings in detail in Fig. 1, 1. and 2 are the antenna and ground connections, respectively, containing an antenna tuning condenser 3 and coupling coil 4 connected in series relation with said antenna and ground. The upper and lower terminals of the coil 4 are connected through conductors 5 and 6, respectively, to the input terminals of a detector tube 7, the output or plate circuit of said tube containing a source of current 8, audio receiving means 9, and a feed back coil 10 connected in series relation. The source of current 8 is at a distance from the receiving set proper and connected therewith over a pair of line wires 11-12, and is of suflicient voltage to act as the usual B battery, for example about 22 volts, the filament, 13, of the detector tube, is connected across the terminals of the common source 8, by way of the line wires 11-12" and a branch circuit consisting of a choke coil 14, variable resistance 15, variable resistance 16, filament 13, and conductor 17.

' The resistance 15 is made sufficient to limit the current supply to the amount required by the filament 13, which resistance, in the present instance is a 400 ohm rheostat, the resistance 16 being the usual filament rheostat of approximately 30 ohms.

In operation, the line wires 11-12 are connected to the terminals 18-19 of the receiving set and the high resistance rheostat 15 adjusted to bring'the filament 13 to approximately the proper working temperature, finer adjustments being made through the smaller resistance 16. This applies current to the filament from the common battery 8 over the following path: Battery 8,

12 tofthe battery. .The circuits being thus suitably energized for receiving, reception is had by a justment of the condenser 3 and feed back. coupling, between coils and- 10', inthe usual manner.

Referring to Fig.2, the circuit arrange of Fig. 2 is identically the same as that described for Fig. 1 except that after the radio receiving set is connected on to the line for energization and tuned in for receiving, the additional audio receiving means 20 and 21 may be connected in at a point on the lineremote from the receiving set, as, for example, a point near the battery 8.

In Fig. 3, which shows the system applied as part of the standard common battery telephone exchange system, the radio receiving circuit is substantially the same as that of Fig. 1 except that the input circuit of the detector tube 7 is inductively coupled to the collecting or antenna circuit through primary and secondary coils 26 and 27, the primary coil 66 being preferably variable and connected in series with an antenna condenser 30 between the aerial 28 and ground connection 29. The output or plate circuit of the detector tube 7 contains the usual audio receiving means 9 and feed back coil 10 connected in series therein and,

in addition, a plug 69 also included in series relation and arranged to engage with a jack 70 connected across the telephone line conductors 1112 terminating'in multiple jacks 71 and 72 at a telephone central oflice, indicated at the right of the vertical dotted lines. The circuit of the filament 13 of the.

detector tube 7 is connected across the terminals of the plug 69 by way of choke coil. 14, resistance 15, resistance 16, filament 13, and conductor 17. The subscribers telephone set 73 is permanently connected to the telephone line 11-12 at the terminal connections 74-75 in the usual manner except that radio choke coils 76-77 are connected in the leads 78-79 extending from the said terminals to the subscribers telephone set. All the circuits and apparatus indicated to the left of the vertical dotted lines in the drawing'are situated at the sub scribers substation.

5 At the central oflice connection is made with the subscribers line 11-12 through the multi 1e jacks by means of a plu '80 constitutingthe answering terminals of an oper-- ators cord circuit of a well known type coil-1;

nected "tothe common battery 8 through]. repeating coils 81 and 82; Bridged across 7 the calling side 83 84 of the'operators' revered cord circuit, through a listening key 85, is an operators telephone receiver 86. For the purpose of applying busy test potential to the test multiple 87 and'operating the usual cut-off relays, not shown, the plugs of the operators cord circuit are provided with the usual tests or sleeve contacts 88-89, the test contact 88 of'the answering plug having, in the present system, connection with a special tone test device 90 of any known or other suitable form operable to produce a characteristic tone in the listening set of an operator testing the line by connecting the tlp of plug with the ring of the jack of a line rendered busy by virtue of the connec-v tion of said tone test therewith.

The combined radio telephone and tele-' phone system for Fig. 3, operates as follows: The subscriber at substation A, desiring to use his radio telephone receiving set, may call the central station either by raising his telephone receiver R from the switch hook in the usual manner, asking for radio service,

at the same time inserting his radio plug 69 in the jack 70, or he ma vibrate his switch hook to indicate his desire without attempting to communicate orally with the operator.

In either case the subscribers line circuit will be closed and the operator'will be signalled in accordance with usual practice. The operator finding that he wants radio service either by his verbal expression of the fact through use of his substation tele hone or by the fact that the line lamp ashes inserts, (or causes to be inserted into one of the subscribers multiple jacks such as 71, by another operator,) the plug 88 of a radio service cord circuit C. When the plug 88 is inserted in the jack 71, late circuit of the subscribers radio tele one receiving set is closed or completed through the telephone central ofice common battery 8 over the following path.- From the plus side of 45 the battery 8 through repeating coil 81,

'plug 8O, jack 71, line wire 11, jack 70,

lug 69, subscribers radio telephone 9, feed ack coil 10,plate and filament of detector tube 7 conductor 17, sleeve contact of jack 69, sieeve contact of plu 70, line conductor '12, sleeve contacts of inc and plug 71-80 and through repeating coil 82 back to battery. 8.. Current for the filament 13 of the subscribers detector tube is also sup lied from the common battery 8 through t e connections just I described extending from the battery terminals to the terminals of the subscribers' radio plug 69, and thence by way of choke coil 14:, res1stancesj15 and 16,,

filament 13, andconductor 17 to the plug 69. The subscribersradio receivingrset being now properly energized for operation it remains only for the subscriber to tune the set in the usual manner as by proper adjustment of the condenser .67, coupling coils the field and not subscribers line is in use for radio telephone service, another subscriber should desire a connection therewith, the operator in imaking the usual busy test by touching the ring contact of one of the subscriber s multiple jack with tip of her calling plug, will receive, instead of the usual busysignal, the characteristic tone test furnished by the tone test device 90 by virtue of the connection thereof throu h the ring contacts of the plug 88 and jack $1 with the multiple test wire 87. Upon receiving this characteristic tone test the operator is apprised of the fact that the line is busy-only for radio telephone service and so proceeds to call the wanted subscriber and establish the connection in the usual way through known or suitable means not shown.

In order to usefully employ the resistance.

loss in the choke coil 14 and resistance 15, the apparatus circuit connection included in the dotted line rectangle of Fig. 3 may be replaced by that of Fig. 4 in which the chokecoil 14 forms the magnet of a dynamic receiver 92 the movable or armature coil 93 of which takes the place of the. telephone receivers 9; 'Where thecoil 14 subserves this double function it may be wound to aresistance sulficiently high to furnish substantially all the resistance needed in the filament circuit and thus usefullyapply the power consumed in reducing the filament current to the amount required. In this case the resistance 15 may be made very small or eliminated entirely. A further advantage of this latter arrangement is that any audio currents passing through the choke coil will act on the field to augment the movements of the armature of the receiver, it being understood of course that the windings are connected in the manner to add their effect to differentially connected. I claim: v 1. In a system of radio broadcast distribution, a subscribers station and a central station and line wires interconnecting them, a telephone, and a radio telephone containing a tube detector at the subscriberss station, a common source at the central station supplying operating current to both telephone and radio telephone at the subscribers station over the said line wires, means at the substation to split the voltage of said commonesource impressed upon the radiogtel'ephone terminals, so as to apply different voltages to the filament circuit and the plate circuit of the detector, together with an in-' ductance coil inserted in the filament branch adapted. to permit the passage of battery rectly to line.

2,. In a system of radio broadcast distribution, a niain station, a substation, line wires interconnecting the two, a radio telephone at' the substation including a tube detector, a source of current at the central station adapted to supply current over. the

line wires at a properwvoltage for the plate circuit, a branch circuit including means to suitably reduce said voltage for the filament circuit, and a receiving telephone connectedto said plate circuit, together with an inductance coil inserted in the filament branch adapted to permit the passage of battery current but to prevent leakage of voice-curcircuit, a branch circuit including means to suitably reduce said voltagefor the filament circuit, an inductance' coil in said branch circuitto prevent leakage of voice currents therethrough and a receiving telephone connected .to said plate circuit, together with a second receiving telephone at the central station adapted to be connected with thelino wires and therebywith the plate circuit at the substation.

4.,In a system of radio broadcast distribution, a main station, a substation, line wires interconnecting the two, a radio telephone at the substation including a tube detector, a source of current at the central station adapted to supply current over the.

line wires at a' proper voltage for the plate circuit, a branch circuit including means to suitably reduce said voltage for the filament circuit, an inductance coil in said branch circuit to prevent leakage of voice currents therethrough-and a receiving telephone connected to said plate circuit, to-

gether with a second receiving telephone at the central station adapted to be connected with the line wires and thereby with the plate circuit at the substation, said second 1 receiving telephone and said source of current at the central station being connectedin parallel.

. 5. In. a system of radio broadcastdistri- I bution, a -main station, a plurality of substations, 'Iheans at the substations including tube detectors for receivlng radio waves, in-

dividual wire circuits-from the main station to the substations with asingle centralized source of current supply for the substation receiving means, connected to, said wire C11- cults 1n parallel and, dlstributlng current thereby to the several substations, with audio choke coils in the common bridge containing said source, each of saidsubstation tube detectors having a tube and a filament circuit connected toreceive current from its wire circuit in parallel, with means in said filament connection or branch to prevent the passage of voice current therethrough.. 6, In a system of radio broadcast distribution, a central station and a substation and metallic circuit line wires interconnecting filament 'current branch containing means to prevent the passage of voice currents therethrough, and the plate circuit finding a return to thefilament through the line wires.

7. In a system of radio broadcast distribution, a central station and a substation and metallic. circuit line wires interconnecting 'the same, a wave collector and a tube detector having a grid circuit properly related to said wave collector, a filament circuit and a plate circuit in proper relation to the grid, a source of current supply at the central station, and parallel me allic branchessat,, 7/ the substation containing the filament and the plate of thedetect'or, to distribute thereto current received over the line wires from the central oflice source, together with means in the filament current branch for chokingout plate current, said plate current finding a return to the filament through the line wires.

8. In a system of radio broadcast distribution, a central station, a common battery thereat, a subscribers station and metallic line wires connecting said subscribers station with said central station and common battery, a radio telephone at the subscribers station, a tube detector, comprisin an input circuit connected to the grid and filament [of said tube, aplate circuitconnected to the plate and through the line wires and central battery to the. filament, and an energizing circuit for the filament, said plate or output circuit, and said filament 3 energizing circuit, being metallically-connected in parallel to the metallic line conductors, a receiving telephone in the plate branch and an inductance device in the filament branch.

9. In a system of radio broadcast distribution, a central station, a common battery thereat, a subscribers station and metallic line wires connecting said subscribers Station with said central station and said common battery, a radio telephone at thel25 subscribers statlon, a tube detector, comprising an input circuit connected to the grid and filament of. said tube, a plate circuit connected tothe plate and through the line wires and said common battery to the 130 energizin allel to t e metallic line conductors, and a' refugee filament, and an energizing circuit for .the filament, said plate or output circuit, and said filament energizing circuit, being metallically connected in parallel to the metallic line conductors, a receiving telephone in the plate branch, and a rheostat and an inductance coil- 'in the filament branch to reduce the voltage of the current supply to the filament and to prevent leak age of voice currents therethrough. 10. In a system of radio broadcast distribution, a central station, a subscribers station and metallic line wires interconnecting them, a radio telephone, at the subscribers station, comprising a tube detector an input circuit connected to the grid and filament of said tube, a plate circuit connected to the plate'and filament, andr an energizing circuit .ior the filament, said plate or output circuit, and said fi ament circuit, being connected in parreceiving telephone composed of two cooperating elements, one included in the plate branch and the other in the filament branch.

11. In a system of radio broadcast distribution, a central station, a subscribers alle 'ment circuit and a telephone metallica ly connected in parallel station and metallic line wires interconnects ing them, a radio telephone at the sub-..

scribers station, comprising a tube detector, an input c rcuit connected to the grid and filament of said tube, a plate circuit con 'nected to the plate andfilament, and an lacircuits, input connections for said grid circuit, and output connections for the said plate circuit, together with a common source of unipotential current connected in parallel to one side of said filament.

through an inductance coil, and to said plate circuit directly,.the' return from the plate circuit to the other side of the filament being through said source of current.

13. In a system of radio broadcast distribution, a central station andsubscriber's stations, and metallic circuit line wires interconnectingthem, a telephone and a radio telephone at a substation connected in parlate circuit in said radio across the radio telephone terminals with an inductance coil connected between one side station ma including t e metallic use wires.

across the said metallic circuit, a file-- of the filament and theline, a common source I of current supply at the central station, means for 'switchmg the same to the subscribers stations through the line circuits, a receiving telephone in the substation radio telephone, and an operators telephone at the central station adapted to be switched into I connection with an individual line while the A source of current is connected thereto. 14. In asystem of radio broadcast distribution, a central station and subscribers stations and metallic line wires interconnecting them, a radio telephone receiver having an 7 audion tube with both filament and plate f circuits metallically connected across the line and a telephone connectedacross the'same air of line wires, at a substation, radio chokmg'means in the telephone bridge, audio choking means in the radio telephone bridge,

and audio choking means between one side of the filament and the corresponding line wire.

. 15 In a system of radio broadcast distri .bution, a central station and subscribers stations and metallic line wires interconnecting them, a radio telephone havinga plate and a filament circuit and a telephone connected same pair of line wires, at a subacross t station, adio choking means in the telephone bridge, and'audio choking means in the radio telephone filament bridge with means at the central station to interconnect the lines in pairs for telephonic conversation, and a common source also at th central station to supply current over the metallic circuit line wires to the subscribers station for all purposes.

16(In a system of radio broadcast distri bution, a central'and a subscribers station and metallic circuit line wires interconnecting them, a radio telephone receiving instrument at the substation including a tube detector with filament and plate circuits metallically connected across the line terminals,

means to prevent shunting of voice currents from the plate circuit throligh the filament circuit, means at the certral station for supplying current to the substation fouall purposes, a telephone in the plate circu t at the substation and a telephone with means to connect it with the said circuit at the central station, said telephones adapted to superimpose audio undulations upon said current supply in the plate circuit, whereby conversation betweenthe central office and the sub- 17. In a system of radio broadcast distribution, a central station and a subscribers station with line wires interconnecting them, a radio tele hone at the substationhaving a high-woun magneto telephone in its plate circuit, connected to the line, and a second high-wound ma eto tele -hone adapted to be coected to e line at t e station,

be carried on over said circuit, f

said high-wound magneto telephones acting bothas transmitters and receivers over the metallic line circuit and through. the high resistance of the plate. circuit.

18. In a systemof radio broadcast distribution, atube detector receiving set having its plate circuit extended to a distant point, and a pair of high-wound magneto telephones directly connected therein, one at the same station with the receiving set, and 10 the other at the distant point, together with a souce of high potential for, said plate circuit also directly connected thereto. v

In testimony whereof I hereunto afiix my signature.

' EDWARD E. CLEMENT. 

